1. Field of the Invention
The present invention is directed to a trailer hitch which has two degrees of freedom for the hitchpoint. The hitchpoint is permitted to move in a lateral direction and is mounted to rotate about a longitudinal axis.
2. Description of the Prior Art
It is conventional to mount a trailer hitch on the back or front of a vehicle, such as a passenger car or truck, to tow a trailer. Conventional trailer hitches are usually classified as bumper hitches, axle hitches, or frame hitches. Each of these hitches consist of a structure which is normally attached to the towing vehicle in a rigid manner. In addition, as is conventional in the trailer hitch art, a hitchball is rigidly affixed to the trailer hitch. The hitchball is a kinematical device which permits articulation between the trailer and the towing vehicle.
Most recent developments in the trailer hitch art have been directed to increasing the strength of the device by increasing the lateral rigidity of the hitch. Further, recent developments have tended to increase the strength of the rear-end of the towing vehicle. As a result of these recent developments, a driver tends to have an increased sense of security while towing a trailer at high speeds. As a result, trailers are often towed at very high speeds and trailer instability develops before the driver realizes what has happened. This situation is extremely dangerous when vehicle control is lost. The trailer often rolls over and correspondingly the trailer hitch tends to also flip over the towing vehicle. This often results in serious injury or death to the occupants of the towing vehicle.
In addition to the conventional trailer hitches discussed above, the Fisher Patent, U.S. Pat. No. 3,510,152, discloses a trailer hitch which will permit free relative pivoting motion while opposing relative pitching and rolling motions. More particularly, the trailer hitch of Fisher provides a means for resisting rolling and pitching movements. This resisting means is a spring which opposes the rolling and pitching motion between the towing vehicle and the towed vehicle. The trailer hitch disclosed by Fisher provides for flexibility only and does not appear to permit a towed vehicle to accidentally overturn while preventing the overturning of the towing vehicle.
The Spanski Patent, U.S. Pat. No. 3,550,710, discloses an innerconnection between two vehicles designed for rough terrain whereby the towing vehicle and the towed vehicle are connected by a spring means and a flexible hose or tube which links together all of the vehicles being towed.
Another prior art patent issued to Almcrantz, U.S. Pat. No. 2,238,095, discloses a means for disconnecting the towing vehicle when the towed vehicle completely overturns. As illustrated in FIG. 2 of Almcrantz, when the towed vehicle is upright the ball 4 is properly seated within the socket 11. However, when the towed vehicle overturns the ball 4 can easily be removed from the socket. This removable connection is possible since the ball 4 is not spherical in shape but rather it is shaped to conform with the shape of the slot 10, as illustrated in FIG. 5 of Almcrantz.